He wasn't on the council for two reasons:1 we would have seen him in TPM.2 He was supposed to be arguementative like Qui-Gon and in TPM Obi-Wan says that if Qui-Gon listened to the council he would have been on it.

According to the [link=http://www.starwars.com/databank/character/countdooku/index.html]Databank[/link] on TOS, Dooku wasn't on the Council. I would think that if Dooku had ever been on the Council, that would be worthy of a mention. Don't you think?